Gearo, I would qualify your statement to stay its unworkable on your system.
I have cut AVCHD on my system with no problems. FCP and PrP are vastly different in how they function.
FCP needs all clips transcoded in order to use them. PrP plays everything natively, no transcoding needed. But it does necessitate systems that maximize the effectiveness of the Mercury Engine. My system does that. Yours might not.
Avid DS / PrP / After Effects Editor
Mac Pro 3,1
2 x 3.2 ghz Quad Core Intel Xeon
Nvidia Quadro 4000
24 gigs ram
Maxx Digital / Areca 8tb. raid
Adobe support has responded to my bug report that there is a known bug with AVCHD footage on the Mac. Through our testing on this thread, the bug seams to only effects Macpro 4.1 and higher systems, thus leading us to believe it is an issue with hyperthreading which the Macpro 3.1 system does not have.
Having used both MacPro 3.1 and 4.1 systems, the 3.1 system is far superior when handling DSLR footage than the 4.1.
Can anyone update or clarify these findings, as to be honest I've kind of just given up editing native DSLR footage on my MacPro 4.1.
I've posted my experience on a few threads, but I'm on a MacPro 4,1 (specs below) and even with the 5.5.2 release, H.264 DSLR footage from a 5D never became workable for me. (It was worse before the update, but it is still massively sluggish and buggy) My answer was to start transcoding to ProRes just like the FCP days for a smooth editing experience.
MacPro 4,1 Quad Core
32 GB RAM
My system has 16g ram, qx9770 extreme,
3 off 10,000 rpm hd in raid 0, cuda mercury gpu support.
If I find results from PP not acceptable with this setup, then surely the average user will find CS5.5 unworkable?
I am trying to confirm timeframes for fix from Adobe as I must have efficient software for my business.